src/Parser/TypeFixer.php
private function spaceSeparatingTypeAndAttributeFix(): ?string
    {
        if ($this->position === 0) {
            return null;
        }

        if ($this->inputString[$this->position] !== ' ') {
            return null;
        }

        return $this->getTypeSubtypeFromPossibleTypeSubtype(
            trim(substr(
                $this->inputString,
                0,
                $this->position
            ), "\t\n\r\0\x0B,") . ';' . substr($this->inputString, $this->position + 1)
        );
    }
private function spaceSeparatingTypeAndAttributeFix(): ?string
    {
        if ($this->position === 0) {
            return null;
        }

        if ($this->inputString[$this->position] !== ' ') {
            return null;
        }

        return $this->getTypeSubtypeFromPossibleTypeSubtype(
            trim(substr(
                $this->inputString,
                0,
                $this->position
            ), "\t\n\r\0\x0B,") . ';' . substr($this->inputString, $this->position + 1)
        );
    }
Attempt to fix media types that are formatted as:

type/subtype attribute=value

i.e. a media type and parameters separated by a space not a semicolon