diff --git a/common/web/gesture-recognizer/src/engine/headless/gestures/matchers/gestureMatcher.ts b/common/web/gesture-recognizer/src/engine/headless/gestures/matchers/gestureMatcher.ts
index 094a5d632d..2a040a1416 100644
--- a/common/web/gesture-recognizer/src/engine/headless/gestures/matchers/gestureMatcher.ts
+++ b/common/web/gesture-recognizer/src/engine/headless/gestures/matchers/gestureMatcher.ts
@@ -178,7 +178,7 @@ export class GestureMatcher<Type, StateToken = any> implements PredecessorMatch<
     return this._isCancelled;
   }
 
-  private finalize(matched: boolean, cause: FulfillmentCause) {
+  private finalize(matched: boolean, cause: FulfillmentCause): MatchResult<Type> {
     if(this.publishedPromise.isFulfilled) {
       return this._result;
     }
@@ -242,6 +242,13 @@ export class GestureMatcher<Type, StateToken = any> implements PredecessorMatch<
       /* c8 ignore next 3 */
     } catch(err) {
       this.publishedPromise.reject(err);
+      return {
+        matched: false,
+        action: {
+          type: 'none',
+          item: null
+        }
+      }
     }
   }
 
diff --git a/common/web/gesture-recognizer/src/engine/touchEventEngine.ts b/common/web/gesture-recognizer/src/engine/touchEventEngine.ts
index 0fe66c3ae5..2dcddffb09 100644
--- a/common/web/gesture-recognizer/src/engine/touchEventEngine.ts
+++ b/common/web/gesture-recognizer/src/engine/touchEventEngine.ts
@@ -227,6 +227,8 @@ export class TouchEventEngine<ItemType, StateToken = any> extends InputEventEngi
         this.inputStartSignalMap.set(touchpoint, eventSignalPromise);
 
         return eventSignalPromise.corePromise;
+      } else {
+        return Promise.resolve();
       }
     });
   }
diff --git a/common/web/input-processor/src/text/prediction/languageProcessor.ts b/common/web/input-processor/src/text/prediction/languageProcessor.ts
index 85485f2273..19f5010806 100644
--- a/common/web/input-processor/src/text/prediction/languageProcessor.ts
+++ b/common/web/input-processor/src/text/prediction/languageProcessor.ts
@@ -167,6 +167,8 @@ export default class LanguageProcessor extends EventEmitter<LanguageProcessorEve
     } else if(outputTarget) {
       let transcription = outputTarget.buildTranscriptionFrom(outputTarget, null, false);
       return this.predict_internal(transcription, true, layerId);
+    } else {
+      return Promise.resolve([]);
     }
   }
 
@@ -284,7 +286,6 @@ export default class LanguageProcessor extends EventEmitter<LanguageProcessorEve
     let original = this.getPredictionState(-reversion.transformId);
     if(!original) {
       console.warn("Could not apply the Suggestion!");
-      return;
     }
 
     // Apply the Reversion!
diff --git a/common/web/input-processor/src/text/prediction/predictionContext.ts b/common/web/input-processor/src/text/prediction/predictionContext.ts
index 2e2dbdd5c5..2b3776792d 100644
--- a/common/web/input-processor/src/text/prediction/predictionContext.ts
+++ b/common/web/input-processor/src/text/prediction/predictionContext.ts
@@ -80,6 +80,8 @@ export default class PredictionContext extends EventEmitter<PredictionContextEve
     this.suggestionApplier = (suggestion) => {
       if(validSuggestionState()) {
         return langProcessor.applySuggestion(suggestion, this.currentTarget, () => kbdProcessor.layerId);
+      } else {
+        return Promise.resolve(null);
       }
     }
 
@@ -243,7 +245,7 @@ export default class PredictionContext extends EventEmitter<PredictionContextEve
    * Should return 'false' if the current state allows reverting a recently-applied suggestion and act accordingly.
    * Otherwise, return true.
    */
-  private doTryRevert = (/*returnObj: {shouldSwallow: boolean}*/): boolean => {
+  private doTryRevert = (/*returnObj: {shouldSwallow: boolean}*/): void => {
     // Has the revert keystroke (BKSP) already been sent once since the last accept?
     if(this.doRevert) {
       // If so, clear the 'revert' option and start doing normal predictions again.
diff --git a/common/web/keyboard-processor/src/text/keyboardProcessor.ts b/common/web/keyboard-processor/src/text/keyboardProcessor.ts
index bdcf4e33a6..ac8bf53b00 100644
--- a/common/web/keyboard-processor/src/text/keyboardProcessor.ts
+++ b/common/web/keyboard-processor/src/text/keyboardProcessor.ts
@@ -443,7 +443,7 @@ export default class KeyboardProcessor extends EventEmitter<EventMap> {
 
     // Do not change layer unless needed (27/08/2015)
     if(id == activeLayer && keyEvent.device.formFactor != DeviceSpec.FormFactor.Desktop) {
-      return false;
+      return;
     }
 
     var idx=id;
diff --git a/common/web/lm-worker/src/main/correction/context-tracker.ts b/common/web/lm-worker/src/main/correction/context-tracker.ts
index b25f727440..2f15165e5e 100644
--- a/common/web/lm-worker/src/main/correction/context-tracker.ts
+++ b/common/web/lm-worker/src/main/correction/context-tracker.ts
@@ -413,7 +413,7 @@ export class ContextTracker extends CircularArray<TrackedContextState> {
           There's already an implied whitespace to the left, so we conceptually
           merge the new whitespace with that one.
         */
-        return state;
+        return;
       } else if(isBackspace) {
         // Consider backspace entry for this case?
         state.replaceTailForBackspace(finalToken, primaryInput.id);
diff --git a/common/web/recorder/src/index.ts b/common/web/recorder/src/index.ts
index c83112e9cb..f776dc1370 100644
--- a/common/web/recorder/src/index.ts
+++ b/common/web/recorder/src/index.ts
@@ -104,6 +104,8 @@ export abstract class RecordedKeystroke {
         return new RecordedPhysicalKeystroke(obj as RecordedPhysicalKeystroke);
       } else if(obj.type == "osk") {
         return new RecordedSyntheticKeystroke(obj as RecordedSyntheticKeystroke);
+      } else {
+        return null;
       }
     }
 
diff --git a/web/src/tsconfig.dom.json b/web/src/tsconfig.dom.json
index 47f2d25016..3c06cfbfbc 100644
--- a/web/src/tsconfig.dom.json
+++ b/web/src/tsconfig.dom.json
@@ -6,6 +6,8 @@
     // TODO: These override ../tsconfig.base.json settings, and so should be removed if possible,
     //       but existing code in web/ breaks some of these settings
     "noImplicitAny": false,
-    "strictFunctionTypes": false
+    "strictFunctionTypes": false,
+    "noImplicitReturns": false,
+    "strictNullChecks": false,
   }
 }
\ No newline at end of file
diff --git a/web/tsconfig.base.json b/web/tsconfig.base.json
index aac6de4f32..e0ed00a89a 100644
--- a/web/tsconfig.base.json
+++ b/web/tsconfig.base.json
@@ -10,11 +10,6 @@
     "lib": ["es6"],
     "target": "es5",
 
-    // TODO: These override ../tsconfig.base.json settings, and so should be removed if possible,
-    //       but existing code in web/ breaks some of these settings
-    "noImplicitReturns": false,
-    "strictNullChecks": false,
-
     // Other settings - declaration files, sourcemapping, and other miscellaneous bits.
     "allowJs": false,
     "declaration": true,