fix: changes to thumb resizing logic

- Resized thumb no longer skews aspect ratio
- Thumbs resized down to maximum thumb size by WIDTH only
- image.checkDimensions() now returns dimensions

src/controllers/uploads.js

@@ -120,12 +120,14 @@ uploadsController.uploadThumb = async function (req, res) {
 			throw new Error('[[error:invalid-file]]');
 		}
 		await image.isFileTypeAllowed(uploadedFile.path);
-		await image.checkDimensions(uploadedFile.path);
+		const dimensions = await image.checkDimensions(uploadedFile.path);
+
+		if (dimensions.width > parseInt(meta.config.topicThumbSize, 10)) {
 			await image.resizeImage({
 				path: uploadedFile.path,
 				width: meta.config.topicThumbSize,
-			height: meta.config.topicThumbSize,
 			});
+		}
 		if (plugins.hooks.hasListeners('filter:uploadImage')) {
 			return await plugins.hooks.fire('filter:uploadImage', {
 				image: uploadedFile,

src/image.js

@@ -105,6 +105,8 @@ image.checkDimensions = async function (path) {
 	if (result.width > meta.config.rejectImageWidth || result.height > meta.config.rejectImageHeight) {
 		throw new Error('[[error:invalid-image-dimensions]]');
 	}
+
+	return result;
 };
 
 image.convertImageToBase64 = async function (path) {