fix contract extension file matching

lib/contracts/compiler.js

@@ -32,7 +32,8 @@ class Compiler {
       function (extension, compiler, callback) {
         // TODO: warn about files it doesn't know how to compile
         let matchingFiles = contractFiles.filter(function (file) {
-          return (file.filename.match(/\.[0-9a-z]+$/)[0] === extension);
+          let fileMatch = file.filename.match(/\.[0-9a-z]+$/);
+          return (fileMatch && (fileMatch[0] === extension));
         });
 
         compiler.call(compiler, matchingFiles || [], function (err, compileResult) {

test_app/app/contracts/invalid_file.sol__tmp__

@@ -0,0 +1,66 @@
+// https://github.com/nexusdev/erc20/blob/master/contracts/base.sol
+
+pragma solidity ^0.4.2;
+contract Token {
+
+  event Transfer(address indexed from, address indexed to, uint value);
+  event Approval( address indexed owner, address indexed spender, uint value);
+
+  mapping( address => uint ) _balances;
+  mapping( address => mapping( address => uint ) ) _approvals;
+  uint public _supply;
+  //uint public _supply2;
+  function Token( uint initial_balance ) {
+    _balances[msg.sender] = initial_balance;
+    _supply = initial_balance;
+  }
+  function totalSupply() constant returns (uint supply) {
+    return _supply;
+  }
+  function balanceOf( address who ) constant returns (uint value) {
+    return _balances[who];
+  }
+  function transfer( address to, uint value) returns (bool ok) {
+    if( _balances[msg.sender] < value ) {
+      throw;
+    }
+    if( !safeToAdd(_balances[to], value) ) {
+      throw;
+    }
+    _balances[msg.sender] -= value;
+    _balances[to] += value;
+    Transfer( msg.sender, to, value );
+    return true;
+  }
+  function transferFrom( address from, address to, uint value) returns (bool ok) {
+    // if you don't have enough balance, throw
+    if( _balances[from] < value ) {
+      throw;
+    }
+    // if you don't have approval, throw
+    if( _approvals[from][msg.sender] < value ) {
+      throw;
+    }
+    if( !safeToAdd(_balances[to], value) ) {
+      throw;
+    }
+    // transfer and return true
+    _approvals[from][msg.sender] -= value;
+    _balances[from] -= value;
+    _balances[to] += value;
+    Transfer( from, to, value );
+    return true;
+  }
+  function approve(address spender, uint value) returns (bool ok) {
+    // TODO: should increase instead
+    _approvals[msg.sender][spender] = value;
+    Approval( msg.sender, spender, value );
+    return true;
+  }
+  function allowance(address owner, address spender) constant returns (uint _allowance) {
+    return _approvals[owner][spender];
+  }
+  function safeToAdd(uint a, uint b) internal returns (bool) {
+    return (a + b >= a);
+  }
+}