message: Improve error messages in ts compiler
  In some cases our compiler created error messages such as:
  Caused by:
  Error: Compilation Errors:
  .../Foo.ts:2:772 - error TS7053: [object Object]
  This commit fixes that by selecting the string property if the object
  containing the error is not a string.
diff: @@ -65,18 +65,20 @@ export async function transpileDirectory(
  function getErrorList(diagnostics: Diagnostic[]): string[] {
  return diagnostics.map(diagnostic => {
  + const text =
  + typeof diagnostic.messageText === 'string'
  + ? diagnostic.messageText
  + : diagnostic.messageText.messageText;
  +
  if (diagnostic.file) {
  const { lineNumber, linePosition } = findPositions(
  diagnostic.file.statements,
  diagnostic.start
  );
  - return `${diagnostic.file.fileName}:${lineNumber}:${linePosition} - error TS${diagnostic.code}: ${diagnostic.messageText}`;
  + return `${diagnostic.file.fileName}:${lineNumber}:${linePosition} - error TS${diagnostic.code}: ${text}`;
  }
  - const text =
  - typeof diagnostic.messageText === 'string'
  - ? diagnostic.messageText
  - : diagnostic.messageText.messageText;
  +
  return `error TS${diagnostic.code}: ${text}`;
  });
  }
  