Fix the code lines mapping

mythril/ether/soliditycontract.py

@@ -109,7 +109,7 @@ class SolidityContract(ETHContract):
         offset = self.mappings[index].offset
         length = self.mappings[index].length
 
-        code = solidity_file.data[offset:offset + length]
+        code = solidity_file.data.encode('utf-8')[offset:offset + length].decode('utf-8')
         lineno = self.mappings[index].lineno
 
         return SourceCodeInfo(filename, lineno, code)

mythril/support/truffle.py

@@ -90,7 +90,7 @@ def analyze_truffle_project(args):
                                 length = mappings[index].length
 
                                 issue.filename = filename
-                                issue.code = source[offset:offset + length]
+                                issue.code = source.encode('utf-8')[offset:offset + length].decode('utf-8')
                                 issue.lineno = mappings[index].lineno
                             except IndexError:
                                 logging.debug("No code mapping at index %d", index)