Reenable other good lints to do with null assertion

Author: jakebailey

.eslintrc.json

@@ -82,8 +82,8 @@
         "@typescript-eslint/type-annotation-spacing": "error",
         "@typescript-eslint/unified-signatures": "error",
 
-        "@typescript-eslint/no-extra-non-null-assertion": "off", // TODO(jakebailey): reenable
-        "@typescript-eslint/no-non-null-asserted-optional-chain": "off", // TODO(jakebailey): reenable
+        "@typescript-eslint/no-extra-non-null-assertion": "error",
+        "@typescript-eslint/no-non-null-asserted-optional-chain": "error",
 
         // scripts/eslint/rules
         "local/object-literal-surrounding-space": "error",

src/compiler/binder.ts

@@ -3041,8 +3041,11 @@ namespace ts {
                 return;
             }
             const rootExpr = getLeftmostAccessExpression(node.left);
-            if (isIdentifier(rootExpr) && lookupSymbolForName(container, rootExpr.escapedText)!?.flags & SymbolFlags.Alias) {
-                return;
+            if (isIdentifier(rootExpr)) {
+                const symbol = lookupSymbolForName(container, rootExpr.escapedText);
+                if (symbol && symbol.flags & SymbolFlags.Alias) {
+                    return;
+                }
             }
             // Fix up parent pointers since we're going to use these nodes before we bind into them
             setParent(node.left, node);
@@ -3074,7 +3077,7 @@ namespace ts {
         }
 
         function bindPotentiallyMissingNamespaces(namespaceSymbol: Symbol | undefined, entityName: BindableStaticNameExpression, isToplevel: boolean, isPrototypeProperty: boolean, containerIsClass: boolean) {
-            if (namespaceSymbol?.flags! & SymbolFlags.Alias) {
+            if (namespaceSymbol && namespaceSymbol.flags & SymbolFlags.Alias) {
                 return namespaceSymbol;
             }
             if (isToplevel && !isPrototypeProperty) {

src/compiler/checker.ts

@@ -5837,8 +5837,8 @@ namespace ts {
                 }
 
                 function preserveCommentsOn<T extends Node>(node: T) {
-                    if (some(propertySymbol.declarations, d => d.kind === SyntaxKind.JSDocPropertyTag)) {
-                        const d = propertySymbol.declarations?.find(d => d.kind === SyntaxKind.JSDocPropertyTag)! as JSDocPropertyTag;
+                    const d = propertySymbol.declarations?.find(d => d.kind === SyntaxKind.JSDocPropertyTag) as JSDocPropertyTag | undefined;
+                    if (d) {
                         const commentText = getTextOfJSDocComment(d.comment);
                         if (commentText) {
                             setSyntheticLeadingComments(node, [{ kind: SyntaxKind.MultiLineCommentTrivia, text: "*\n * " + commentText.replace(/\n/g, "\n * ") + "\n ", pos: -1, end: -1, hasTrailingNewLine: true }]);

src/compiler/transformers/declarations.ts

@@ -218,9 +218,9 @@ namespace ts {
         }
 
         function reportNonlocalAugmentation(containingFile: SourceFile, parentSymbol: Symbol, symbol: Symbol) {
-            const primaryDeclaration = parentSymbol.declarations?.find(d => getSourceFileOfNode(d) === containingFile)!;
+            const primaryDeclaration = parentSymbol.declarations?.find(d => getSourceFileOfNode(d) === containingFile);
             const augmentingDeclarations = filter(symbol.declarations, d => getSourceFileOfNode(d) !== containingFile);
-            if (augmentingDeclarations) {
+            if (primaryDeclaration && augmentingDeclarations) {
                 for (const augmentations of augmentingDeclarations) {
                     context.addDiagnostic(addRelatedInfo(
                         createDiagnosticForNode(augmentations, Diagnostics.Declaration_augments_declaration_in_another_file_This_cannot_be_serialized),