Merge pull request TypeStrong#127 from joshpcausey/master

File system lag can cause Invalid source file errors to slip through

Author: piotr-oles

src/IncrementalChecker.ts

@@ -238,7 +238,13 @@ class IncrementalChecker {
       try {
         this.linter.lint(fileName, undefined, this.linterConfig);
       } catch (e) {
-        if (fs.existsSync(fileName)) {
+        if (
+            fs.existsSync(fileName) &&
+            // check the error type due to file system lag
+            !(e instanceof Error) &&
+            !(e.constructor.name === 'FatalError') &&
+            !(e.message && e.message.trim().startsWith("Invalid source file"))
+        ) {
           // it's not because file doesn't exist - throw error
           throw e;
         }