chore: enable more linters and address their findings.

.golangci.yml

@@ -1,11 +1,15 @@
 linters:
-  # Disable all default linters and enable only revive and formatters before
-  # new findings by default linters are addressed.
-  disable-all: true
   enable:
+    - dupword
+    - errcheck
+    - errname
+    - godot
     - gofumpt
     - goimports
+    - misspell
     - revive
+    - unconvert
+    - unused
 
 issues:
   exclude-use-default: false

parser.go

@@ -11,7 +11,7 @@ import (
 )
 
 // ErrHelp is the error returned if the -help or -h flag is invoked but no such flag is defined.
-// Alias for flag.ErrHelp
+// Alias for flag.ErrHelp.
 var ErrHelp = flag.ErrHelp
 
 // Parser registers and parses configuration values.

value/floats.go

@@ -43,10 +43,10 @@ func (iv *float64Value) Set(val string) error {
 		return err
 	}
 
-	*iv.dest = float64(num)
+	*iv.dest = num
 	return nil
 }
 
 func (iv *float64Value) String() string {
-	return strconv.FormatFloat(float64(*iv.dest), 'G', -1, 64)
+	return strconv.FormatFloat(*iv.dest, 'G', -1, 64)
 }