fix: runtime bug fix (#361)

Author: kneekey23

Packages/ClientRuntime/Sources/Networking/Http/HttpContext.swift

@@ -26,8 +26,8 @@ public struct HttpContext: MiddlewareContext {
         return attributes.get(key: AttributeKey<ResponseDecoder>(name: "Decoder"))!
     }
 
-    public func getHost() -> String {
-        return attributes.get(key: AttributeKey<String>(name: "Host"))!
+    public func getHost() -> String? {
+        return attributes.get(key: AttributeKey<String>(name: "Host"))
     }
 
     public func getServiceName() -> String {

smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/integration/HttpUrlPathMiddleware.kt

@@ -90,10 +90,10 @@ class HttpUrlPathMiddleware(
                 resolvedURIComponents.add(it.content)
             }
         }
-        writer.write("let hostCustomPath = URL(string: \"http://\\(context.getHost())\")?.path")
+
         val uri = resolvedURIComponents.joinToString(separator = "/", prefix = "/", postfix = "")
         writer.write("var urlPath = \"\$L\"", uri)
-        writer.openBlock("if let hostCustomPath = hostCustomPath, !hostCustomPath.isEmpty {", "}") {
+        writer.openBlock("if let host = context.getHost(), let hostCustomPath = URL(string: \"http://\\(host)\")?.path, !hostCustomPath.isEmpty {", "}") {
             writer.write("urlPath = \"\\(hostCustomPath)\\(urlPath)\"")
         }
         writer.write("var copiedContext = context")

smithy-swift-codegen/src/test/kotlin/HttpUrlPathMiddlewareTests.kt

@@ -28,9 +28,8 @@ class HttpUrlPathMiddlewareTests {
                     guard let label1 = input.label1 else {
                         return .failure(.client(ClientRuntime.ClientError.pathCreationFailed(("label1 is nil and needs a value for the path of this operation"))))
                     }
-                    let hostCustomPath = URL(string: "http://\(context.getHost())")?.path
                     var urlPath = "/smoketest/\(label1.urlPercentEncoding())/foo"
-                    if let hostCustomPath = hostCustomPath, !hostCustomPath.isEmpty {
+                    if let host = context.getHost(), let hostCustomPath = URL(string: "http://\(host)")?.path, !hostCustomPath.isEmpty {
                         urlPath = "\(hostCustomPath)\(urlPath)"
                     }
                     var copiedContext = context