Merge pull request #6823 from SimonBrandner/fix/emoji-dupe/19073

Fix last character duplication with `Automatically replace plain text emoji` on

src/components/views/rooms/BasicMessageComposer.tsx

@@ -181,16 +181,18 @@ export default class BasicMessageEditor extends React.Component<IProps, IState>
 
             if (data) {
                 const { partCreator } = model;
-                const moveStart = emoticonMatch[0][0] === " " ? 1 : 0;
-                const moveEnd = emoticonMatch[0].length - emoticonMatch.length - moveStart;
+                const firstMatch = emoticonMatch[0];
+                const moveStart = firstMatch[0] === " " ? 1 : 0;
 
                 // we need the range to only comprise of the emoticon
                 // because we'll replace the whole range with an emoji,
                 // so move the start forward to the start of the emoticon.
                 // Take + 1 because index is reported without the possible preceding space.
                 range.moveStartForwards(emoticonMatch.index + moveStart);
-                // and move end backwards so that we don't replace the trailing space/newline
-                range.moveEndBackwards(moveEnd);
+                // If the end is a trailing space/newline move end backwards, so that we don't replace it
+                if (["\n", " "].includes(firstMatch[firstMatch.length - 1])) {
+                    range.moveEndBackwards(1);
+                }
 
                 // this returns the amount of added/removed characters during the replace
                 // so the caret position can be adjusted.