Add better exceptions message for failing transactions.

bin/vyper-run

@@ -1,5 +1,7 @@
 #!/usr/bin/env python3.6
 import argparse
+import sys
+import os
 import vyper
 from collections import Counter
 from pprint import pprint
@@ -20,6 +22,11 @@ from web3 import (
     Web3,
 )
 
+sys.tracebacklimit = 0
+tb_limit = os.environ.get('VYPER_TRACEBACK_LIMIT')
+if tb_limit:
+    sys.tracebacklimit = int(tb_limit)
+
 aparser = argparse.ArgumentParser(description='Vyper {0} quick CLI runner'.format(vyper.__version__))
 aparser.add_argument('input_file', help='Vyper sourcecode to run')
 aparser.add_argument('call_list', help='call list, without parameters: func, with parameters func(1, 2, 3). Semicolon separated')

vdb/debug_computation.py

@@ -5,6 +5,20 @@ from evm.exceptions import (
     Halt,
 )
 from vdb.vdb import VyperDebugCmd
+from evm.exceptions import VMError
+from vyper.exceptions import ParserException
+
+
+class DebugVMError(VMError, ParserException):
+    lineno = None
+    col_offset = None
+
+    def __init__(self, message, item=None, source_code=None):
+        self.message = message
+        if item is not None:
+            self.lineno, self.col_offset = item
+        if source_code is not None:
+            self.source_code = source_code.splitlines()
 
 
 class DebugComputation(ByzantiumComputation):
@@ -27,10 +41,17 @@ class DebugComputation(ByzantiumComputation):
         return line_no
 
     @classmethod
-    def get_line_no(cls, pc):
+    def get_pos(cls, pc):
         pc_pos_map = cls.source_map['line_number_map']['pc_pos_map']
         if pc in pc_pos_map:
-            return pc_pos_map[pc][0]
+            return pc_pos_map[pc]
+
+    @classmethod
+    def get_line_no(cls, pc):
+        pos = cls.get_pos(pc)
+        if pos:
+            return pos[0]
+        return None
 
     @classmethod
     def is_breakpoint(cls, pc, continue_line_nos):
@@ -72,6 +93,16 @@ class DebugComputation(ByzantiumComputation):
 
                 try:
                     opcode_fn(computation=computation)
+                except VMError as e:  # re-raise with more details.
+                    pos = cls.get_pos(pc_to_execute)
+                    msg = e.args[0]
+                    msg = "" if len(msg) == 0 else msg
+                    # import ipdb; ipdb.set_trace()
+                    raise DebugVMError(
+                        message=msg,
+                        item=pos,
+                        source_code=cls.source_code
+                    ) from e
                 except Halt:
                     break