Added return after reject.

src/utils/utils.js

@@ -541,13 +541,15 @@ export function injectScript(tabId, scriptfile, cssfile, runAt) {
 			if (chrome.runtime.lastError) {
 				log('injectScript error', chrome.runtime.lastError);
 				reject(new Error(chrome.runtime.lastError));
+				return;
 			}
 
 			if (cssfile) {
 				chrome.tabs.insertCSS(tabId, { file: cssfile, runAt }, () => {
 					if (chrome.runtime.lastError) {
 						log('insertCSS error', chrome.runtime.lastError);
 						reject(new Error(chrome.runtime.lastError));
+						return;
 					}
 					resolve();
 				});