Add error handling example.

Introduction.md

@@ -111,10 +111,10 @@ a table or struct. Note that symbols, keywords and strings are all immutable. Be
 code easier to reason about, it allows for many optimizations involving these types.
 
 ```lisp
-# Prints true
+# Evaluates to true
 (= :hello :hello) 
 
-# Prints false, everything in janet is case sensitive
+# Evaluates to false, everything in janet is case sensitive
 (= :hello :HeLlO) 
 
 # Look up into a table - evaluates to 25
@@ -586,6 +586,24 @@ are simply propagated to the next fiber.
 (print (resume f)) # -> throws an error because the fiber is dead
 ```
 
+## Using Fibers to Capture Errors
+
+Besides being used as coroutines, fibers can be used to implement error handling (exceptions).
+
+```lisp
+(defn my-function-that-errors [x]
+ (print "start function with " x)
+ (error "oops!")
+ (print "never gets here"))
+
+# Use the :e flag to only trap errors.
+(def f (fiber.new my-function-that-errors :e))
+(def result (resume f))
+(if (= (fiber.status f) :error)
+ (print "result contains the error")
+ (print "result contains the good result"))
+```
+
 # Macros
 
 :)