Component/s field not properly setting using Behaviours

import com.atlassian.jira.bc.project.component.ProjectComponent
import com.atlassian.jira.component.ComponentAccessor


def componentsField = getFieldById("components")
def descriptionField = getFieldById("description")

if (componentsField.getFormValue() instanceof String) {
    String value = componentsField.getFormValue()
    
    if (value.startsWith("nv")) {
        componentsField.setFormValue("")
    }
} else if (componentsField.getFormValue() instanceof List) {
    String value = componentsField.getFormValue().toString()
    
    componentsField.setFormValue([])
    
    StringTokenizer st = new StringTokenizer(value, ",")
    
    List<Long> newValues = new ArrayList<>();
    
    while (st.hasMoreTokens()) {
        String token = st.nextToken().trim()
        
        if (!token.startsWith("nv_")) {
            if (token.startsWith("[")) {
                token = token.substring(1, token.length())
            }
            
            if (token.endsWith("]")) {
                token = token.substring(0, token.length() - 1)
            }
            
            newValues.add(Long.parseLong(token))
        }
        
    }
    
    if (newValues.size() == 1) {
        componentsField.setFormValue(newValues)
    } else {
        componentsField.setFormValue(newValues.join(","))
    }
    
    descriptionField.setFormValue(newValues.toString())
    
}