qt send tab: show friendlier error on mistyped bitcoin address

electrum/gui/qt/main_window.py

@@ -1486,9 +1486,16 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, Logger):
         if not pr:
             errors = self.payto_e.get_errors()
             if errors:
-                self.show_warning(_("Invalid Lines found:") + "\n\n" +
+                if len(errors) == 1 and not errors[0].is_multiline:
-                                  '\n'.join([_("Line #") + f"{err.idx+1}: {err.line_content[:40]}... ({repr(err.exc)})"
+                    err = errors[0]
-                                             for err in errors]))
+                    self.show_warning(_("Failed to parse 'Pay to' line") + ":\n" +
+                                      f"{err.line_content[:40]}...\n\n"
+                                      f"{err.exc!r}")
+                else:
+                    self.show_warning(_("Invalid Lines found:") + "\n\n" +
+                                      '\n'.join([_("Line #") +
+                                                 f"{err.idx+1}: {err.line_content[:40]}... ({err.exc!r})"
+                                                 for err in errors]))
                 return True
 
             if self.payto_e.is_alias and self.payto_e.validated is False:

electrum/gui/qt/paytoedit.py

@@ -52,9 +52,10 @@ normal_style = "QPlainTextEdit { }"
 
 
 class PayToLineError(NamedTuple):
-    idx: int  # index of line
     line_content: str
     exc: Exception
+    idx: int = 0  # index of line
+    is_multiline: bool = False
 
 
 class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
@@ -93,7 +94,10 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         self.setStyleSheet(util.ColorScheme.RED.as_stylesheet(True))
 
     def parse_address_and_amount(self, line) -> PartialTxOutput:
-        x, y = line.split(',')
+        try:
+            x, y = line.split(',')
+        except ValueError:
+            raise Exception("expected two comma-separated values: (address, amount)") from None
         scriptpubkey = self.parse_output(x)
         amount = self.parse_amount(y)
         return PartialTxOutput(scriptpubkey=scriptpubkey, value=amount)
@@ -102,9 +106,14 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
         try:
             address = self.parse_address(x)
             return bfh(bitcoin.address_to_script(address))
-        except:
+        except Exception:
+            pass
+        try:
             script = self.parse_script(x)
             return bfh(script)
+        except Exception:
+            pass
+        raise Exception("Invalid address or script.")
 
     def parse_script(self, x):
         script = ''
@@ -150,25 +159,27 @@ class PayToEdit(CompletionTextEdit, ScanQRTextEdit, Logger):
                 try:
                     self.win.parse_lightning_invoice(bolt11_invoice)
                 except LnDecodeException as e:
-                    self.errors.append(PayToLineError(idx=0, line_content=data, exc=e))
+                    self.errors.append(PayToLineError(line_content=data, exc=e))
                 else:
                     self.lightning_invoice = bolt11_invoice
                 return
             try:
                 self.payto_scriptpubkey = self.parse_output(data)
-            except:
+            except Exception as e:
-                pass
+                self.errors.append(PayToLineError(line_content=data, exc=e))
             if self.payto_scriptpubkey:
                 self.win.set_onchain(True)
                 self.win.lock_amount(False)
-                return
+            return
 
+        # there are multiple lines
         is_max = False
         for i, line in enumerate(lines):
             try:
                 output = self.parse_address_and_amount(line)
             except Exception as e:
-                self.errors.append(PayToLineError(idx=i, line_content=line.strip(), exc=e))
+                self.errors.append(PayToLineError(
+                    idx=i, line_content=line.strip(), exc=e, is_multiline=True))
                 continue
             outputs.append(output)
             if output.value == '!':