Fix exec sql exception issue. (#3982)

### What problem does this PR solve?
#3978

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

agent/canvas.py

@@ -206,7 +206,12 @@ class Canvas(ABC):
                                 waiting.append(c)
                             continue
                     yield "*'{}'* is running...🕞".format(self.get_compnent_name(c))
-                    ans = cpn.run(self.history, **kwargs)
+                    try:
+                        ans = cpn.run(self.history, **kwargs)
+                    except Exception as e:
+                        logging.exception(f"Canvas.run got exception: {e}")
+                        self.path[-1].append(c)
+                        raise e
                     self.path[-1].append(c)
             ran += 1
 
@@ -228,20 +233,12 @@ class Canvas(ABC):
                 switch_out = cpn["obj"].output()[1].iloc[0, 0]
                 assert switch_out in self.components, \
                     "{}'s output: {} not valid.".format(cpn_id, switch_out)
-                try:
-                    for m in prepare2run([switch_out]):
-                        yield {"content": m, "running_status": True}
-                except Exception as e:
-                    logging.exception("Canvas.run got exception")
-                    raise e
+                for m in prepare2run([switch_out]):
+                    yield {"content": m, "running_status": True}
                 continue
 
-            try:
-                for m in prepare2run(cpn["downstream"]):
-                    yield {"content": m, "running_status": True}
-            except Exception as e:
-                logging.exception("Canvas.run got exception")
-                raise e
+            for m in prepare2run(cpn["downstream"]):
+                yield {"content": m, "running_status": True}
 
             if ran >= len(self.path[-1]) and waiting:
                 without_dependent_checking = waiting

agent/component/exesql.py

@@ -64,7 +64,7 @@ class ExeSQL(ComponentBase, ABC):
         self._loop += 1
 
         ans = self.get_input()
-        ans = "".join(ans["content"]) if "content" in ans else ""
+        ans = "".join([str(a) for a in ans["content"]]) if "content" in ans else ""
         ans = re.sub(r'^.*?SELECT ', 'SELECT ', repr(ans), flags=re.IGNORECASE)
         ans = re.sub(r';.*?SELECT ', '; SELECT ', ans, flags=re.IGNORECASE)
         ans = re.sub(r';[^;]*$', r';', ans)