fixed a bug with wrong LaTeX input

mathbot/rendering.py

@@ -20,11 +20,18 @@ from io import BytesIO
 import matplotlib
 matplotlib.use("Agg")
 import matplotlib.pyplot as plt
+import importlib
 
 
 def get_png(tex):
+	importlib.reload(plt)
 	buf = BytesIO()
 
+	exc = None
+
+	try:
+		plt.subplot()
+
 		plt.text(0, 0.6, r"$%s$" % tex, fontsize = 50)
 		fig = plt.gca()                                                                 
 		fig.axes.get_xaxis().set_visible(False)                                         
@@ -34,7 +41,13 @@ def get_png(tex):
 
 		buf.seek(0)
 
+	except Exception as e:
+		exc = e
+	finally:
 		plt.clf()
 
+	if(exc):
+		raise exc
+
 	return buf