handling cases none printable characters and fix index out of range error

Runtime/service/keyboard.cs

             }
 
             var currentEvent = Event.current;
+           
+            
             if (currentEvent != null && currentEvent.type == EventType.KeyDown) {
                 var action = TextInputUtils.getInputAction(currentEvent);
                 if (action != null) {
                 if (action == null || action == TextInputAction.newline) {
                     if (currentEvent.keyCode == KeyCode.None) {
-                        this._value = this._value.clearCompose().insert(new string(currentEvent.character, 1));
+                        char ch = currentEvent.character;
+                        if (ch == '\r' || ch == 3) {
+                            ch = '\n';
+                        }
+                        this._value = this._value.clearCompose();
+                        if (_validateCharacter(ch)) {
+                            this._value = this._value.insert(new string(ch, 1));
+                        } 
                         Window.instance.run(() => { TextInput._updateEditingState(this._client, this._value); });
                     }
                 }
         }
 
         public void Dispose() {
+        }
+
+        static bool _validateCharacter(char ch) {
+            return ch >= ' ' || ch == '\t' || ch == '\r' || ch == 10 || ch == '\n';
         }
     }
     

Runtime/service/text_input.cs

                 return this;
             }
 
-            newText = this.selection.textBefore(this.text) + text + this.selection.textAfter(this.text);
-            newSelection = TextSelection.collapsed(this.selection.start + text.Length);
+            var selection = this.selection;
+            if (selection.start < 0) {
+                selection = TextSelection.collapsed(0, this.selection.affinity);
+            }
+            newText = selection.textBefore(this.text) + text + selection.textAfter(this.text);
+            newSelection = TextSelection.collapsed(selection.start + text.Length);
             return new TextEditingValue(
                 text: newText, selection: newSelection, composing: TextRange.empty
             );

Runtime/ui/painting/txt/font_manager.cs

     
     public static class FontExtension  
     {  
-        public static CharacterInfo mustGetCharacterInfo(this Font font, char ch, int fontSize, UnityEngine.FontStyle fontStyle)  
+        public static CharacterInfo getCharacterInfo(this Font font, char ch, int fontSize, UnityEngine.FontStyle fontStyle)  
-            D.assert(success, $"fail to get character info for character '{ch}' (code{(int)ch}) from font: ${font.name}");
+            if (!success) {  
+                Debug.LogWarning($"character info not found from the given font: character '{ch}' (code{(int)ch}) font: ${font.name}");     
+            }
-        }  
+        }
     }
 }

Runtime/ui/painting/txt/mesh_generator.cs

                     continue;
                 }
 
-                CharacterInfo charInfo = font.mustGetCharacterInfo(ch, fontSizeToLoad, style.UnityFontStyle);
+                CharacterInfo charInfo = font.getCharacterInfo(ch, fontSizeToLoad, style.UnityFontStyle);
                 var minX = charInfo.minX / this._scale;
                 var maxX = charInfo.maxX / this._scale;
                 var minY = charInfo.minY / this._scale;

Runtime/ui/txt/layout.cs

             for (int i = 0; i < count; i++) {
                 int charIndex = start + i;
                 var ch = text[charIndex];
-                CharacterInfo characterInfo = font.mustGetCharacterInfo(ch, style.UnityFontSize, style.UnityFontStyle);
+                CharacterInfo characterInfo = font.getCharacterInfo(ch, style.UnityFontSize, style.UnityFontStyle);
 
                 var rect = Rect.fromLTRB(characterInfo.minX, -characterInfo.maxY, characterInfo.maxX,
                     -characterInfo.minY);

Runtime/ui/txt/linebreaker.cs

 
             if (this._tabWidth == int.MaxValue) {
                 this._font.RequestCharactersInTexture(" ", this._fontSize);
-                CharacterInfo characterInfo = this._font.mustGetCharacterInfo(' ', this._fontSize, UnityEngine.FontStyle.Normal);
+                CharacterInfo characterInfo = this._font.getCharacterInfo(' ', this._fontSize, UnityEngine.FontStyle.Normal);
                 this._tabWidth = characterInfo.advance * kTabSpaceCount;
             }