Fix false positive rewriteRelativeImportExtensions error on non-TS extensions (#60415)

Author: andrewbranch

src/compiler/utilities.ts

@@ -4306,7 +4306,7 @@ export function tryGetImportFromModuleSpecifier(node: StringLiteralLike): AnyVal
 
 /** @internal */
 export function shouldRewriteModuleSpecifier(specifier: string, compilerOptions: CompilerOptions): boolean {
-    return !!compilerOptions.rewriteRelativeImportExtensions && pathIsRelative(specifier) && !isDeclarationFileName(specifier);
+    return !!compilerOptions.rewriteRelativeImportExtensions && pathIsRelative(specifier) && !isDeclarationFileName(specifier) && hasTSFileExtension(specifier);
 }
 
 /** @internal */

tests/baselines/reference/nonTSExtensions.js

@@ -0,0 +1,14 @@
+//// [tests/cases/conformance/externalModules/rewriteRelativeImportExtensions/nonTSExtensions.ts] ////
+
+//// [example.json]
+{}
+
+//// [styles.d.css.ts]
+export {};
+
+//// [index.mts]
+import {} from "./example.json" with { type: "json" }; // Ok
+import {} from "./styles.css"; // Ok
+
+//// [index.mjs]
+export {};

tests/cases/conformance/externalModules/rewriteRelativeImportExtensions/nonTSExtensions.ts

@@ -0,0 +1,15 @@
+// @module: nodenext
+// @rewriteRelativeImportExtensions: true
+// @allowArbitraryExtensions: true
+// @resolveJsonModule: true
+// @noTypesAndSymbols: true
+
+// @Filename: example.json
+{}
+
+// @Filename: styles.d.css.ts
+export {};
+
+// @Filename: index.mts
+import {} from "./example.json" with { type: "json" }; // Ok
+import {} from "./styles.css"; // Ok