fix(material/form-field): error text fix

fixed issue where certain screen reader and browser pairings do not recognize mat-error being inserted into
the DOM, changed it to where visibility is changing on the wrapper rather than adding and removing the
hint and error wrappers. the changing of visibility should be recognized by all browser and screen reader
pairings

Fixes angular#29616

Author: DBowen33

src/material/form-field/form-field.html

@@ -99,25 +99,22 @@
   class="mat-mdc-form-field-subscript-wrapper mat-mdc-form-field-bottom-align"
   [class.mat-mdc-form-field-subscript-dynamic-size]="subscriptSizing === 'dynamic'"
 >
-  @switch (_getDisplayedMessages()) {
-    @case ('error') {
-      <div
-        class="mat-mdc-form-field-error-wrapper"
-        [@transitionMessages]="_subscriptAnimationState"
-      >
-        <ng-content select="mat-error, [matError]"></ng-content>
-      </div>
-    }
-
-    @case ('hint') {
-      <div class="mat-mdc-form-field-hint-wrapper" [@transitionMessages]="_subscriptAnimationState">
-        @if (hintLabel) {
-          <mat-hint [id]="_hintLabelId">{{hintLabel}}</mat-hint>
-        }
-        <ng-content select="mat-hint:not([align='end'])"></ng-content>
-        <div class="mat-mdc-form-field-hint-spacer"></div>
-        <ng-content select="mat-hint[align='end']"></ng-content>
-      </div>
+  <div
+    class="mat-mdc-form-field-error-wrapper mat-mdc-form-field-error-wrapper--hidden"
+    [@transitionMessages]="_subscriptAnimationState"
+  >
+    <ng-content select="mat-error, [matError]"></ng-content>
+  </div>
+    
+  <div 
+    class="mat-mdc-form-field-hint-wrapper mat-mdc-form-field-hint-wrapper--hidden" 
+    [@transitionMessages]="_subscriptAnimationState"
+  >
+    @if (hintLabel) {
+      <mat-hint [id]="_hintLabelId">{{hintLabel}}</mat-hint>
     }
-  }
+    <ng-content select="mat-hint:not([align='end'])"></ng-content>
+    <div class="mat-mdc-form-field-hint-spacer"></div>
+    <ng-content select="mat-hint[align='end']"></ng-content>
+  </div>
 </div>

src/material/form-field/form-field.scss

@@ -218,3 +218,11 @@ $_icon-prefix-infix-padding: 4px;
 .mdc-notched-outline--upgraded .mdc-floating-label--float-above {
   max-width: calc(100% * 4 / 3 + 1px);
 }
+
+.mat-mdc-form-field-error-wrapper--hidden {
+  visibility: hidden;
+}
+
+.mat-mdc-form-field-hint-wrapper--hidden {
+  visibility: hidden;
+}

src/material/form-field/form-field.ts

@@ -437,6 +437,7 @@ export class MatFormField
     this._stateChanges = control.stateChanges.subscribe(() => {
       this._updateFocusState();
       this._syncDescribedByIds();
+      this._showOrHideSubscript();
       this._changeDetectorRef.markForCheck();
     });
 
@@ -478,17 +479,20 @@ export class MatFormField
     // Re-validate when the number of hints changes.
     this._hintChildren.changes.subscribe(() => {
       this._processHints();
+      this._showOrHideSubscript();
       this._changeDetectorRef.markForCheck();
     });
 
     // Update the aria-described by when the number of errors changes.
     this._errorChildren.changes.subscribe(() => {
       this._syncDescribedByIds();
+      this._showOrHideSubscript();
       this._changeDetectorRef.markForCheck();
     });
 
     // Initial mat-hint validation and subscript describedByIds sync.
     this._validateHints();
+    this._showOrHideSubscript();
     this._syncDescribedByIds();
   }
 
@@ -682,6 +686,45 @@ export class MatFormField
     }
   }
 
+  /**
+   * Solves https://github.com/angular/components/issues/29616
+   * Issues with certain browser and screen reader pairings not able to announce mat-error
+   * when it's added to the DOM rather than changing the visibility of the hint/error wrappers.
+   * Changing visibility instead of adding the div wrappers works for all browsers and sreen
+   * readers.
+   *
+   * If there is an 'error' or 'hint' message being returned, remove visibility: hidden
+   * style class and show error or hint section of code. If no 'error' or 'hint' messages are
+   * being returned and no error children showing in query list, add visibility: hidden
+   * style class back to error wrapper.
+   */
+  private _showOrHideSubscript() {
+    switch (this._getDisplayedMessages()) {
+      case 'error': {
+        console.log(this._elementRef.nativeElement.children[1].children[0].classList);
+        this._elementRef.nativeElement.children[1].children[0].classList.remove(
+          'mat-mdc-form-field-error-wrapper--hidden',
+        );
+        console.log(this._elementRef.nativeElement.children[1].children[0].classList);
+        break;
+      }
+      case 'hint': {
+        console.log(this._elementRef.nativeElement.children[1].children[1].classList);
+        this._elementRef.nativeElement.children[1].children[1].classList.remove(
+          'mat-mdc-form-field-hint-wrapper--hidden',
+        );
+        console.log(this._elementRef.nativeElement.children[1].children[1].classList);
+        break;
+      }
+    }
+
+    if (!this._errorChildren || this._errorChildren.length === 0 || !this._control.errorState) {
+      this._elementRef.nativeElement.children[1].children[0].classList.add(
+        'mat-mdc-form-field-error-wrapper--hidden',
+      );
+    }
+  }
+
   /**
    * Updates the horizontal offset of the label in the outline appearance. In the outline
    * appearance, the notched-outline and label are not relative to the infix container because