using error reporter from environment to handle syntax errors

Sources/Environment.swift

@@ -3,9 +3,15 @@ public struct Environment {
   public var extensions: [Extension]
 
   public var loader: Loader?
+  public var errorReporter: ErrorReporter
 
-  public init(loader: Loader? = nil, extensions: [Extension]? = nil, templateClass: Template.Type = Template.self) {
+  public init(loader: Loader? = nil,
+              extensions: [Extension]? = nil,
+              templateClass: Template.Type = Template.self,
+              errorReporter: ErrorReporter = SimpleErrorReporter()) {
+    
     self.templateClass = templateClass
+    self.errorReporter = errorReporter
     self.loader = loader
     self.extensions = (extensions ?? []) + [DefaultExtension()]
   }
@@ -28,11 +34,21 @@ public struct Environment {
 
   public func renderTemplate(name: String, context: [String: Any]? = nil) throws -> String {
     let template = try loadTemplate(name: name)
-    return try template.render(context)
+    return try render(template: template, context: context)
   }
 
   public func renderTemplate(string: String, context: [String: Any]? = nil) throws -> String {
     let template = templateClass.init(templateString: string, environment: self)
-    return try template.render(context)
+    return try render(template: template, context: context)
+  }
+  
+  func render(template: Template, context: [String: Any]?) throws -> String {
+    errorReporter.context = ErrorReporterContext(template: template)
+    do {
+      return try template.render(context)
+    } catch {
+      try errorReporter.report(error: error)
+      return ""
+    }
   }
 }