Typed Throws example fixes (#2278)

* Fixed `firstNameResultFromArray` example code in Proposal 0413: Typed Throws

* Replace erroneous tabs with spaces in example code in Proposal 0413: Typed Throws

Author: rtharston

proposals/0413-typed-throws.md

@@ -311,11 +311,11 @@ func firstNameResultFromArray(_ array: [String]) throws(FirstNameError) -> Strin
 
 func userResultFromStrings(strings: [String]) throws(SimpleError) -> User  {
     do {
-        let firstName = try stringFromArray(strings, at: 0, errorMessage: "Missing first name")
+        let firstName = try firstNameResultFromArray(strings)
         return User(firstName: firstName, lastName: "")        
     } catch {
         // error is a `FirstNameError`, map it to a `SimpleError`.
-        throw SimpleError(message: "First name is missing")
+        throw SimpleError(message: "Missing first name")
     }
 }
 ```
@@ -365,7 +365,7 @@ func countNodes(in tree: Node, matching predicate: (Node) throws -> Bool) rethro
     }
 
     override func visit(node: Node) {
-    	do {
+      do {
         if try predicate(node) {
           count = count + 1
         }
@@ -420,7 +420,7 @@ func countNodes<E: Error>(in tree: Node, matching predicate: (Node) throws(E) ->
     }
 
     override func visit(node: Node) {
-    	do {
+      do {
         if try predicate(node) {
           count = count + 1
         }
@@ -1091,7 +1091,7 @@ func load(from dataLoader: dataLoader) {
   do {
     try dataLoader.load()
   } catch {
-  	processError(error)
+    processError(error)
   }
 }
 ```
@@ -1117,7 +1117,7 @@ func load(from dataLoader: dataLoader) {
   do {
     try dataLoader.load()
   } catch {
-  	processError(error)
+    processError(error)
   }
 }
 ```