Migration of jsx files to tsx 3 (#851)

This is in continue to:
- #850
- #848

The last files should be converted as part of this PR, there are only a
handful left.

src/components/FieldSource.tsx

@@ -7,9 +7,9 @@ import InputAutocomplete from './InputAutocomplete'
 type FieldSourceProps = {
   value?: string
   wdKey?: string
-  onChange?(...args: unknown[]): unknown
+  onChange?(value: string| undefined): unknown
   sourceIds?: unknown[]
-  error?: unknown[]
+  error?: {message: string}
 };
 
 export default class FieldSource extends React.Component<FieldSourceProps> {