Script automatically remove extra spaces at the beginning and end of a selected text layer.

@Kathyyyy , please remember to mark the correct answer as such. 

When I type, I often have extra spaces at the beginning and end of each line when I press enter, because we have to manually line break.

Why would that cause spaces to manifest? 

Is that a peculiarity of the used font/language?

Could you provide a file as is and the corresponding one as it should be? 

You should be able to use a regular expression with a global flag and multi-line flag, replacing the white space with nothing:

^\s+|\s+$

Perhaps like this (script code courtesy of @Lumigraphics)

/*
Utility PS Scripts created by David M. Converse ©2018-21

This script is a demo of replacing text

Last modified 6/2/2021

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#target photoshop

layerUpdate();

function layerUpdate(){
    if(documents.length > 0){
        var originalDialogMode = app.displayDialogs;
        app.displayDialogs = DialogModes.ERROR;
        var originalRulerUnits = preferences.rulerUnits;
        try{
            var docRef = activeDocument;
            preferences.rulerUnits = Units.POINTS;
            for(var i = 0; i < docRef.artLayers.length; i++){
                var LayerRef = docRef.artLayers[i];
                if(LayerRef.kind == LayerKind.TEXT){
                    var TextRef = LayerRef.textItem;
                    var layerText = TextRef.contents;
                    var newText = layerText.replace(/^\s+|\s+$/gm, "");
                    TextRef.contents= newText;
                    }
                }
            preferences.rulerUnits = originalRulerUnits;
            app.displayDialogs = originalDialogMode;
            }
        catch(e){
            }
        }
    }