how to locate this syntax error : SyntaxError: Assigning to rvalue at

When trying to build my vu3js SPA I get the following error

vite v2.9.12 building for production… ✓ 75 modules transformed.

[rollup-plugin-dynamic-import-variables] Assigning to rvalue (1907:44)

file:
/ORIGINAL-P1/LARAVEL-BREW/BrewersCompanion/vue/src/components/RecipeEditor.vue:1907:44

error during build:

SyntaxError: Assigning to rvalue (1907:44)

at Parser.pp$4.raise (/ORIGINAL-P1/LARAVEL-BREW/BrewersCompanion/vue/node_modules/rollup/dist/shared/rollup.js:19738:13)
at Parser.pp$7.toAssignable (/ORIGINAL-P1/LARAVEL-BREW/BrewersCompanion/vue/node_modules/rollup/dist/shared/rollup.js:18231:12)
at Parser.pp$5.parseMaybeAssign (/ORIGINAL-P1/LARAVEL-BREW/BrewersCompanion/vue/node_modules/rollup/dist/shared/rollup.js:18754:21)
at Parser.pp$5.parseParenAndDistinguishExpression (/ORIGINAL-P1/LARAVEL-BREW/BrewersCompanion/vue/node_modules/rollup/dist/shared/rollup.js:19209:28)
at Parser.pp$5.parseExprAtom (/ORIGINAL-P1/LARAVEL-BREW/BrewersCompanion/vue/node_modules/rollup/dist/shared/rollup.js:19072:41)
at Parser.pp$5.parseExprSubscripts (/ORIGINAL-P1/LARAVEL-BREW/BrewersCompanion/vue/node_modules/rollup/dist/shared/rollup.js:18905:19)
at Parser.pp$5.parseMaybeUnary (/ORIGINAL-P1/LARAVEL-BREW/BrewersCompanion/vue/node_modules/rollup/dist/shared/rollup.js:18871:17)
at Parser.pp$5.parseExprOps (/ORIGINAL-P1/LARAVEL-BREW/BrewersCompanion/vue/node_modules/rollup/dist/shared/rollup.js:18798:19)
at Parser.pp$5.parseMaybeConditional (/ORIGINAL-P1/LARAVEL-BREW/BrewersCompanion/vue/node_modules/rollup/dist/shared/rollup.js:18781:19)
at Parser.pp$5.parseMaybeAssign (/ORIGINAL-P1/LARAVEL-BREW/BrewersCompanion/vue/node_modules/rollup/dist/shared/rollup.js:18748:19)

I cannot see anything like assigning to right hand value around line 1907

Here is a chunk of code starting at line 1905

//Gravity (line 1905)
let fixed_og = ref();

let showConfirmGravity = ref(false);
function adaptFermentablesToNewGravity() {
    let equipment = store.getters["equipment/getEquipmentById"](
        recipe_model.equipment
    );
    let old_extract_added_to_boil = extract_added_to_boil.value;
    let old_extract_from_mash = extract_from_mash.value;
    let P = SGToPlato(recipe_model.original_gravity);
  
    if (P < 1) {
        P = 1;
    }
    //original gravity is for postboil volume
    let new_extract_mass = extract_mass_from_platos_and_volume(
        P,
        postboil_volume_reverse_cold.value
    );
    //FOR MASH
    let new_extract_from_mash =
        (new_extract_mass * old_extract_from_mash) /
        (old_extract_added_to_boil + old_extract_from_mash);

    recipe_model.fermentables.forEach((element) => {
        if (element.use === "mash") {
            element.quantity =
                1 *
                (element.quantity / old_extract_from_mash) *
                new_extract_from_mash;
        }
    });

    //FOR BOIL
    let new_extract_added_at_boil =
        (new_extract_mass * old_extract_added_to_boil) /
        (old_extract_added_to_boil + old_extract_from_mash);

    recipe_model.fermentables.forEach((element) => {
        if (element.use === "boil" || element.use === "steep") {
            element.quantity =
                1 *
                (element.quantity / old_extract_added_to_boil) *
                new_extract_added_at_boil;
        }
    });
}

Could somebody help me finding where the problem is located ?