command: Improve error messages to be Git-agnostic

The command package is not only used to spawn Git commands, but may also
spawn any other arbitrary command. It's thus quite misleading that some
of the error messages are mentioninng "GitCommand"s as context.

Reword these errors to be command-agnostic. While at it, let's also use
the `%w` formatter to chain errors together.

2 files changed, 8 insertions, 5 deletions

diff --git a/internal/command/command.go b/internal/command/command.go
index 61d7fb6ef..abf008f3d 100644
--- a/internal/command/command.go
+++ b/internal/command/command.go
@@ -214,8 +214,9 @@ func New(ctx context.Context, cmd *exec.Cmd, opts ...Option) (*Command, error) {
 	if _, ok := cfg.stdin.(stdinSentinel); ok {
 		pipe, err := cmd.StdinPipe()
 		if err != nil {
-			return nil, fmt.Errorf("GitCommand: stdin: %v", err)
+			return nil, fmt.Errorf("creating stdin pipe: %w", err)
 		}
+
 		command.writer = pipe
 	} else if cfg.stdin != nil {
 		cmd.Stdin = cfg.stdin
@@ -228,8 +229,9 @@ func New(ctx context.Context, cmd *exec.Cmd, opts ...Option) (*Command, error) {
 	} else {
 		pipe, err := cmd.StdoutPipe()
 		if err != nil {
-			return nil, fmt.Errorf("GitCommand: stdout: %v", err)
+			return nil, fmt.Errorf("creating stdout pipe: %w", err)
 		}
+
 		command.reader = pipe
 	}
 
@@ -238,13 +240,14 @@ func New(ctx context.Context, cmd *exec.Cmd, opts ...Option) (*Command, error) {
 	} else {
 		command.stderrBuffer, err = newStderrBuffer(maxStderrBytes, maxStderrLineLength, []byte("\n"))
 		if err != nil {
-			return nil, fmt.Errorf("GitCommand: failed to create stderr buffer: %v", err)
+			return nil, fmt.Errorf("creating stderr buffer: %w", err)
 		}
+
 		cmd.Stderr = command.stderrBuffer
 	}
 
 	if err := cmd.Start(); err != nil {
-		return nil, fmt.Errorf("GitCommand: start %v: %v", cmd.Args, err)
+		return nil, fmt.Errorf("starting process %v: %w", cmd.Args, err)
 	}
 
 	inFlightCommandGauge.Inc()
diff --git a/internal/command/command_test.go b/internal/command/command_test.go
index 5ac1aed85..1f6eae3b0 100644
--- a/internal/command/command_test.go
+++ b/internal/command/command_test.go
@@ -254,7 +254,7 @@ func TestNew_missingBinary(t *testing.T) {
 	ctx := testhelper.Context(t)
 
 	cmd, err := New(ctx, exec.Command("command-non-existent"))
-	require.Equal(t, fmt.Errorf("GitCommand: start [command-non-existent]: exec: \"command-non-existent\": executable file not found in $PATH"), err)
+	require.EqualError(t, err, "starting process [command-non-existent]: exec: \"command-non-existent\": executable file not found in $PATH")
 	require.Nil(t, cmd)
 }