fix: type-check included files missed by transform (type-only files)

- type-only files never get processed by Rollup as their imports are
  elided/removed by TS in the resulting compiled JS file
  - so, as a workaround, make sure that all files in the `tsconfig`
    `include` (i.e. in `parsedConfig.fileNames`) are also type-checked
    - note that this will not catch _all_ type-only imports, in
      particular if one is using `tsconfig` `files` (or in general _not_
      using glob patterns in `include`) -- this is just a workaround,
      that requires a separate fix
  - we do the same process for generating declarations for "missed"
    files right now in `_onwrite`, so basically do the same thing but
    for type-checking in `_ongenerate`

(_technically_ speaking, there could be full TS files
(i.e. _not_ type-only) that are in the `include` and weren't
transformed
- these would basically be independent TS files not part of the bundle
  that the user wanted type-checking and declarations for (as we
  _already_ generate declarations for those files))

src/index.ts

@@ -282,6 +282,23 @@ const typescript: PluginImpl<RPT2Options> = (options) =>
 				});
 			}
 
+			// type-check missed files as well
+			parsedConfig.fileNames.forEach((name) =>
+			{
+				if (!pluginOptions.check)
+					return;
+
+				const key = normalize(name);
+				if (key in declarations || !filter(key)) // don't duplicate if it's already been transformed
+					return;
+
+				context.debug(() => `type-checking missed '${key}'`);
+
+				const snapshot = servicesHost.getScriptSnapshot(key);
+				if (snapshot)
+					typecheckFile(key, snapshot, context);
+			});
+
 			if (!watchMode && !noErrors)
 				context.info(yellow("there were errors or warnings."));