Tweak message text

Author: amcasey

src/services/services.ts

@@ -1158,7 +1158,7 @@ namespace ts {
         function getValidSourceFile(fileName: string): SourceFile {
             const sourceFile = program.getSourceFile(fileName);
             if (!sourceFile) {
-                const error: Error & PossibleProgramFileInfo = new Error(`Could not find sourceFile: '${fileName}'.`);
+                const error: Error & PossibleProgramFileInfo = new Error(`Could not find source file: '${fileName}'.`);
 
                 // We've been having trouble debugging this, so attach sidecar data for the tsserver log.
                 // See https://github.com/microsoft/TypeScript/issues/30180.

src/testRunner/unittests/tsserver/cachingFileSystemInformation.ts

@@ -139,7 +139,7 @@ namespace ts.projectSystem {
                 assert.isTrue(false, `should not find file '${imported.path}'`);
             }
             catch (e) {
-                assert.isTrue(e.message.indexOf(`Could not find sourceFile: '${imported.path}'.`) === 0, `Actual: ${e.message}`);
+                assert.isTrue(e.message.indexOf(`Could not find source file: '${imported.path}'.`) === 0, `Actual: ${e.message}`);
             }
             const f2Lookups = getLocationsForModuleLookup("f2");
             callsTrackingHost.verifyCalledOnEachEntryNTimes(CalledMapsWithSingleArg.fileExists, f2Lookups, 1);