Compile with -Werror

Author: Chris Hellmuth

source/MaterialXGenOslNodes/OslNodesShaderGenerator.cpp

@@ -45,7 +45,7 @@ ShaderPtr OslNodesShaderGenerator::generate(const string& name, ElementPtr eleme
     ConstDocumentPtr document = element->getDocument();
 
     string lastNodeName;
-    ShaderOutput* lastOutput;
+    ShaderOutput* lastOutput = nullptr;
     std::vector<string> connections;
 
     std::set<std::string> osoPaths;
@@ -104,6 +104,11 @@ ShaderPtr OslNodesShaderGenerator::generate(const string& name, ElementPtr eleme
         lastNodeName = name;
     }
 
+    if (!lastOutput) {
+        printf("Invalid shader\n");
+        return nullptr;
+    }
+
     for (auto&& connect : connections) {
         emitLine(connect, stage, false);
     }

source/MaterialXGenOslNodes/OslNodesSyntax.cpp

@@ -32,7 +32,7 @@ class OslNodesVectorTypeSyntax : public AggregateTypeSyntax
 
         string result = "";
         string separator = "";
-        for (int i = 0; i < c.numElements(); i++) {
+        for (size_t i = 0; i < c.numElements(); i++) {
             result += separator;
             result += toValueString(c[i]);