fuzzer: do runtime nil check for args, instead of older emitted nil c…

…hecks

README.md

@@ -26,9 +26,10 @@ $ go install golang.org/dl/gotip@latest
 $ gotip download
 ```
 
-Download, compile, and install the fzgen binary from source:
+Download and install the fzgen binary from source, as well as add its fuzzer to our go.mod:
 ```
 $ go install github.com/thepudds/fzgen/cmd/fzgen@latest
+$ go get github.com/thepudds/fzgen/fuzzer
 ```
 
 Use fzgen to automatically create a set of fuzz targets -- in this case for the encoding/ascii85 package from the Go standard library:
@@ -56,10 +57,10 @@ That's enough for you to get started on your own, but let's also briefly look at
 
 ## Example: Easily Finding a Data Race
 
-Again starting from an empty directory, we'll set up a module, and this time also add fzgen to the go.mod:
+Again starting from an empty directory, we'll set up a module, and add the fzgen fuzzer to go.mod:
 ```
 $ go mod init temp
-$ go get go get github.com/thepudds/fzgen
+$ go get github.com/thepudds/fzgen/fuzzer
 ```
 
 Next, we automatically create a new fuzz target. This time:

examples/inputs/race/race.go

@@ -7,7 +7,7 @@
 //     3. The two Loads must happen concurrently.
 //     4. Prior to the two Loads, no other Store can update the key to have a non-matching payload.
 //
-// Using the fzgen/fuzzer.Chain created by default via 'fzgen -chain -parallel -pkg=github.com/thepudds/fzgen/examples/inputs/race',
+// Using the fzgen/fuzzer.Chain created by default via 'fzgen -chain -parallel github.com/thepudds/fzgen/examples/inputs/race',
 // this data race is typically caught after a few minutes of fuzzing with '-race' when starting from scratch.
 package raceexample
 
@@ -32,7 +32,7 @@ func (m *MySafeMap) Load(key [16]byte) *Request {
 	if ok {
 		req := r.(*Request)
 		if req.Answer == 42 {
-			// DATA RACE (but requires: matching store/load keys, and concurrent matching load keys, and certain payload data)
+			// DATA RACE (but detection requires: matching store/load keys, and concurrent matching load keys, and certain payload data)
 			req.deepQuestion++
 		}
 		return req