cmd/go,crypto/mlkem,crypto/x509,encoding/ascii85: clean up tautological/impossible nil conditions

Change-Id: I3cdc599ebc93f5c9be5645e7ef7ce167242d9c1b
Reviewed-on: https://go-review.googlesource.com/c/go/+/739800
Reviewed-by: Roland Shoemaker <roland@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

6 files changed, 19 insertions, 35 deletions

diff --git a/src/cmd/go/internal/imports/read_test.go b/src/cmd/go/internal/imports/read_test.go
index 6a1a6524a1..b1247cc490 100644
--- a/src/cmd/go/internal/imports/read_test.go
+++ b/src/cmd/go/internal/imports/read_test.go
@@ -146,7 +146,7 @@ func testRead(t *testing.T, tests []readTest, read func(io.Reader) ([]byte, erro
 			}
 			continue
 		}
-		if err == nil && tt.err != "" {
+		if tt.err != "" {
 			t.Errorf("#%d: success, expected %q", i, tt.err)
 			continue
 		}
diff --git a/src/cmd/go/internal/load/godebug.go b/src/cmd/go/internal/load/godebug.go
index 817cc4faeb..7bb873fa7d 100644
--- a/src/cmd/go/internal/load/godebug.go
+++ b/src/cmd/go/internal/load/godebug.go
@@ -66,10 +66,7 @@ func defaultGODEBUG(loaderstate *modload.State, p *Package, directives, testDire
 	// If GOFIPS140 is set to anything but "off",
 	// default to GODEBUG=fips140=on.
 	if fips140.Enabled() {
-		if m == nil {
-			m = make(map[string]string)
-		}
-		m["fips140"] = "on"
+		m = map[string]string{"fips140": "on"}
 	}
 
 	// Add directives from main module go.mod.
diff --git a/src/cmd/internal/script/engine.go b/src/cmd/internal/script/engine.go
index 05b9433d3e..9480741c10 100644
--- a/src/cmd/internal/script/engine.go
+++ b/src/cmd/internal/script/engine.go
@@ -580,23 +580,21 @@ func (e *Engine) runCommand(s *State, cmd *command, impl Cmd) error {
 		return nil
 	}
 
-	if wait != nil {
-		stdout, stderr, waitErr := wait(s)
-		s.stdout = stdout
-		s.stderr = stderr
-		if stdout != "" {
-			s.Logf("[stdout]\n%s", stdout)
-		}
-		if stderr != "" {
-			s.Logf("[stderr]\n%s", stderr)
-		}
-		if cmdErr := checkStatus(cmd, waitErr); cmdErr != nil {
-			return cmdErr
-		}
-		if waitErr != nil {
-			// waitErr was expected (by cmd.want), so log it instead of returning it.
-			s.Logf("[%v]\n", waitErr)
-		}
+	stdout, stderr, waitErr := wait(s)
+	s.stdout = stdout
+	s.stderr = stderr
+	if stdout != "" {
+		s.Logf("[stdout]\n%s", stdout)
+	}
+	if stderr != "" {
+		s.Logf("[stderr]\n%s", stderr)
+	}
+	if cmdErr := checkStatus(cmd, waitErr); cmdErr != nil {
+		return cmdErr
+	}
+	if waitErr != nil {
+		// waitErr was expected (by cmd.want), so log it instead of returning it.
+		s.Logf("[%v]\n", waitErr)
 	}
 	return nil
 }
diff --git a/src/crypto/mlkem/mlkem_test.go b/src/crypto/mlkem/mlkem_test.go
index 922147ab15..e1c2ef49f1 100644
--- a/src/crypto/mlkem/mlkem_test.go
+++ b/src/crypto/mlkem/mlkem_test.go
@@ -274,9 +274,6 @@ func BenchmarkRoundTrip(b *testing.B) {
 	ek := dk.EncapsulationKey()
 	ekBytes := ek.Bytes()
 	_, c := ek.Encapsulate()
-	if err != nil {
-		b.Fatal(err)
-	}
 	b.Run("Alice", func(b *testing.B) {
 		for i := 0; i < b.N; i++ {
 			dkS, err := GenerateKey768()
@@ -300,9 +297,6 @@ func BenchmarkRoundTrip(b *testing.B) {
 				b.Fatal(err)
 			}
 			Ks, cS := ek.Encapsulate()
-			if err != nil {
-				b.Fatal(err)
-			}
 			sink ^= cS[0] ^ Ks[0]
 		}
 	})
diff --git a/src/crypto/x509/root_unix_test.go b/src/crypto/x509/root_unix_test.go
index b03a03d116..b04f09d179 100644
--- a/src/crypto/x509/root_unix_test.go
+++ b/src/crypto/x509/root_unix_test.go
@@ -30,9 +30,7 @@ func TestEnvVars(t *testing.T) {
 		t.Fatalf("failed to read test cert: %s", err)
 	}
 	if err := os.WriteFile(filepath.Join(tmpDir, testFile), testCert, 0644); err != nil {
-		if err != nil {
-			t.Fatalf("failed to write test cert: %s", err)
-		}
+		t.Fatalf("failed to write test cert: %s", err)
 	}
 
 	testCases := []struct {
diff --git a/src/encoding/ascii85/ascii85_test.go b/src/encoding/ascii85/ascii85_test.go
index 578829eecc..66445ada26 100644
--- a/src/encoding/ascii85/ascii85_test.go
+++ b/src/encoding/ascii85/ascii85_test.go
@@ -119,13 +119,10 @@ func TestDecoder(t *testing.T) {
 		decoder := NewDecoder(strings.NewReader(p.encoded))
 		dbuf, err := io.ReadAll(decoder)
 		if err != nil {
-			t.Fatal("Read failed", err)
+			t.Fatalf("Read from %q = %v, want nil", p.encoded, err)
 		}
 		testEqual(t, "Read from %q = length %v, want %v", p.encoded, len(dbuf), len(p.decoded))
 		testEqual(t, "Decoding of %q = %q, want %q", p.encoded, string(dbuf), p.decoded)
-		if err != nil {
-			testEqual(t, "Read from %q = %v, want %v", p.encoded, err, io.EOF)
-		}
 	}
 }