[FIX] mail: force the model when creating basic thread

fw of ca6cc05cec13f2e3f1d6555491c3180e9ff3ace2

closes odoo/odoo#60645

Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>
Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

addons/mail/static/src/models/composer/composer.js

@@ -673,9 +673,11 @@ function factory(dependencies) {
             this.update({
                 suggestedChannels: [[
                     'insert-and-replace',
-                    mentions.map(data =>
-                        this.env.models['mail.thread'].convertData(data))
-                    ]],
+                    mentions.map(data => {
+                        const threadData = this.env.models['mail.thread'].convertData(data);
+                        return Object.assign({ model: 'mail.channel' }, threadData);
+                    })
+                ]],
             });
 
             if (this.suggestedChannels[0]) {

addons/mail/static/src/models/messaging_initializer/messaging_initializer.js

@@ -163,7 +163,9 @@ function factory(dependencies) {
                     // channels received at init.
                     convertedData.members = [['link', this.env.messaging.currentPartner]];
                 }
-                const channel = this.env.models['mail.thread'].insert(convertedData);
+                const channel = this.env.models['mail.thread'].insert(
+                    Object.assign({ model: 'mail.channel' }, convertedData)
+                );
                 // flux specific: channels received at init have to be
                 // considered pinned. task-2284357
                 if (!channel.isPinned) {