[CONSUMERBANK-528] Handle invalid phone numbers in Link signup more gracefully

StripeFinancialConnections/StripeFinancialConnections/Source/Native/LinkLogin/LinkLoginViewController.swift

@@ -179,6 +179,7 @@ final class LinkLoginViewController: UIViewController {
                         }
                     } else {
                         formView?.showAndEditPhoneNumberFieldIfNeeded()
+                        setContinueWithLinkButtonDisabledState()
                     }
                 case .failure(let error):
                     self.delegate?.linkLoginViewController(self, didReceiveTerminalError: error)
@@ -210,7 +211,21 @@ final class LinkLoginViewController: UIViewController {
             case .success(let response):
                 self.delegate?.linkLoginViewController(self, signedUpAttachedAndSynchronized: response)
             case .failure(let error):
-                self.delegate?.linkLoginViewController(self, didReceiveTerminalError: error)
+                func completeWithTerminalError() {
+                    self.delegate?.linkLoginViewController(self, didReceiveTerminalError: error)
+                }
+
+                guard let stripeError = error as? StripeError, case .apiError(let stripeAPIError) = stripeError else {
+                    return completeWithTerminalError()
+                }
+
+                // Hack to determine if the error is related to the phone number.
+                // If so, show a generic error message under the phone textfield.
+                if let errorMessage = stripeAPIError.message, errorMessage.contains("phone") {
+                    formView.phoneTextField.setErrorText(PhoneTextField.LocalizedStrings.invalidPhoneNumber)
+                } else {
+                    completeWithTerminalError()
+                }
             }
         }
     }

StripeFinancialConnections/StripeFinancialConnections/Source/Native/NetworkingLinkSignupPane/LinkSignupFormView.swift

@@ -194,6 +194,7 @@ extension LinkSignupFormView: PhoneTextFieldDelegate {
         _ phoneTextField: PhoneTextField,
         didChangePhoneNumber phoneNumber: PhoneNumber?
     ) {
+        phoneTextField.clearErrorText()
         delegate?.linkSignupFormViewDidUpdateFields(self)
     }
 }

StripeFinancialConnections/StripeFinancialConnections/Source/Native/NetworkingLinkSignupPane/PhoneTextField.swift

@@ -19,9 +19,21 @@ protocol PhoneTextFieldDelegate: AnyObject {
 
 final class PhoneTextField: UIView {
 
+    enum LocalizedStrings {
+        static let textfieldPlaceholder = STPLocalizedString(
+            "Phone number",
+            "The title of a user-input-field that appears when a user is signing up to Link (a payment service). It instructs user to type a phone number."
+        )
+
+        static let invalidPhoneNumber = STPLocalizedString(
+            "Your mobile phone number is invalid.",
+            "An error message that instructs the user to keep typing their phone number in a user-input field."
+        )
+    }
+
     fileprivate lazy var textField: RoundedTextField = {
         let textField = RoundedTextField(
-            placeholder: STPLocalizedString("Phone number", "The title of a user-input-field that appears when a user is signing up to Link (a payment service). It instructs user to type a phone number."),
+            placeholder: LocalizedStrings.textfieldPlaceholder,
             showDoneToolbar: true,
             theme: theme
         )
@@ -158,13 +170,21 @@ final class PhoneTextField: UIView {
                 if text.isEmpty {
                     // no error message if empty
                 } else {
-                    textField.errorText = STPLocalizedString("Your mobile phone number is incomplete.", "An error message that instructs the user to keep typing their phone number in a user-input field.")
+                    textField.errorText = LocalizedStrings.invalidPhoneNumber
                 }
             }
         }
 
         delegate?.phoneTextField(self, didChangePhoneNumber: phoneNumber)
     }
+
+    func setErrorText(_ errorMessage: String) {
+        textField.errorText = errorMessage
+    }
+
+    func clearErrorText() {
+        textField.errorText = nil
+    }
 }
 
 // MARK: - RoundedTextFieldDelegate